Corrosion resistance of a superhydrophobic dodecyltrimethoxysilane coating on magnesium alloy AZ31 fabricated by one-step electrodeposition

Abstract

A superhydrophobic and corrosion-resistant coating with hierarchical macro/nanostructures was constructed by one-step electrodeposition of dodecyltrimethoxysilane (e-DTMS) on Mg alloy AZ31 in a relatively media. The surface morphology and chemical composition were characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Surface wettability was evaluated by measuring water contact angles and sliding angles of water droplets. The protective performance was measured by electrochemical and hydrogen evolution tests. The results indicated that the e-DTMS coating had excellent self-cleaning performance with a contact angle of 158° ± 2.3° and a sliding angle of 4° ± 0.5°. The superhydrophobic surface greatly reduced the contact area between the AZ31 substrate and water, and it was chemically stable in corrosive media. The corrosion current density (2.11 × 10⁻⁷ A cm⁻²) of the e-DTMS coating was about three hundred times less than that of the AZ31 substrate (7.34 × 10⁻⁵ A cm⁻²). The results demonstrated that the e-DTMS coating remarkably enhanced the anti-corrosion performance of AZ31 alloys.